Underwater earth boring mechanism



Sep`t. 29, 1959 E. w. SMITH UNDERWATER EARTH BORING MECHANISM 3Sheets-Sheet 1 Filed March 24, 1954 e f x n L//- ,f

Ilm my o1 wf mi E. W. SMITH UNDERWATER EARTH BORING MECHANISM sept. 29,1959 3 sheets-sheet 2 Filed March 24, 1954 INVENTOR. Edmn /,Smh Y N uw;n

sept; 29, 1959 E. w. SMITH 2,906,502

UNDERWATER EARTH BORING MECHANISM Filed March 24, 1954 3 Sheets-Sheet 3United States Patent O 2,906,502 UNDERWATER EARTH BRING MECHANISM EdwardW. Smith, Melrose Highlands, Mass. Application March 24, 1954, SerialNo. 418,286 15 Claims. (Cl. Z55-2.5)

'I'he present invention relates to earth boring equipment and proceduresand more particularly to a method and means for performing thisoperation when the area of earth to be bored is submerged to substantialdepths in water.

As is well known, the constant search for oil bearing .structures hasresulted in prospecting for oil, not only on land surfaces which showedevidence of containing them, but also in areas such as the Gulf ofMexico where the oil bearing structures may be covered by substantialdepths of water. While drilling in these areas can be accomplished bythe usual rotary rig and procedures providing the depths of Water arereasonably low, say less than 30 feet, it is a much more diiicultproblem in greater depths.

This diculty is essentially due to the fact that the usual earth boringequipment consists of a tool or cutting element, mounted on the end of apiece of drill pipe, the Whole being suspended from a rotary table whichlikewise serves to revolve the drill pipe and hence the tool. It isobvious that such an arrangement presupposes some sort of a rigid bed onwhich the rotary table can be mounted and permit of a rigid connectionbetween the turn table `and the tool by means of the drill pipe. Such anarrangement cannot be provided from a boat or other floating structure,because wave motion, yawing of the boat, etc., and similar disturbingmotions preclude the possibility of maintaining reasonably accuratealignment between the axis of the turntable and axis of the hole beingdrilled.

One of the purposes of the present invention is to provide a method andmeans for earth boring under such conditions which does not require theaccurate alignment of various elements with the hole being drilled.

Another object of, the invention is to pro-vide a method and means forsupplying a ow of drilling mud to the drilling tool and returning it tothe surface to the usual type of slush pit Without danger of admixtureof the drilling mud with sea water.

Another object of the invention is to provide in effect a exible drillpipe for carrying the drilling mud to the tool and simultaneouslyproviding support for the tool.

Still another object of the invention is to provide a novel tool drivingmechanism operated by drilling mud, in which the power necessary for theactual drilling is generated at the tool rather than being transmittedby a rigid drill pipe from the surface.

Still another object of the invention is to provide a means wherebydrilling can be accomplished by high frequency oscillation of thedrilling tool rather than by continued rotation of the tool as usuallyunderstood.

These and other advantages of the present invention will be more clearlyunderstood in connection with the drawings, in which:

Figure l is a longitudinal cross sectional view of the drilling unittaken on the line 1-1 of Figure 2.

Figure 1A is a perspective exploded view of two elements of the drillingunit.

p 2,906,502 Patented sept. 29, 1959 Figures 1B and 1C are schematicdiagrams used in explanation of the structure of the drilling unit.

Figure 2 is a cross sectional view of the drilling unit taken along theline 2-2 of Figure 1.

Figure 3 is a cross section taken along the line 3-3 of Figure 1.

Figure 4 is a cross sectional view of the ilexible pipe supporting thedrilling unit.

Figure 5 is a section taken along the line 5 5 of Figure 4.

Figure 6 is an end view of the flexible pipe segment of Figure 4.

Figure 7 is a cross sectional elevation of the elements positioned inthe floating support.

Figure 8 is a side elevation of the elements shown in Figure 7.

Figure 9 is a detail of the flexible pipe supporting elements at theocean bottom, and

Figure l0 shows a diagrammatic View of a means for anchoring thesupporting barge.

Referring to Figure l, there is shown a drilling unit to which a cuttingtool may be attached at the lower end 1 and which is supported at itsupper end 2 by a exible tube element 50, Figure 4. The threaded portion31 of the upper end 2 threads into the recessed portion 28 of theilexible tube forming a continuous elongated member. This threadedportion 31 is shaped to thread into and be securely held in thelowermost of the interchangeable portions 28 as indicated more fullyhereinafter. In this drilling unit there is a mass or backing element 3having a fairly large moment of inertia. This backing element iscylindrical in shape and forms the upper end of the drilling unit. Adownwardly projecting annular ange 3 of the backing element has threadedto its inner lower side a cylindrical tube 4. Within the lower end ofthis cylindrical tube 4 but not secured directly to it is a tool drivingelement S, which compared with the backing element has a smaller momentof inertia. This driving element S is cylindrical in shape withprojecting ribs 12 and is secured to the backing element 3 by means of asteel tube 6, which tube extends through and is secured by welding orother suitable means at its lower end to the inner wall of the drivingelement 5 and at its upper end 7 to the inner wall of the backingelement 3. This tube 6 has a substantial torsional resilience whichpermits torsional oscillation of the tool driving element 5 with respectto the backing element 3 in a manner hereinafter described.

From the lower end of the tool driving element 5, there is provided anextension forming a projecting tube member 8 with a centrally locatedopening 9 continuous with the center of the tube 6. The lower end ofthis projecting tube 8 is provided with a head 8a for securing thecutting tool 70 suitably aligned with the opening 9. At the lower end ofthe tube 4, tnere is secured by suitable means, a cylinder 10A havingstepped milled slots 10', substantially dividing the cylinder into `apair of semicylindrical sections 32 and 33 formed with angular arcs ofsomething less than The milled slots do not extend the entire length ofthe cylinder 10A as is illustrated in Figure 1A. The longitudinal edgesof these sections are formed with shoulders 34 and 35. When thesesections 32 and 33 are secured to the tube the slots 10 formed betweentheir end edges may each be considered as comprising a recess section 10and a recess section 11, as schematically illustrated in Figure 1B withthe recess section 10 centrally located longitudinally with respect tothe recess section 11. It will be noted therefore that recess sections10 and 11 are portions of slots 10.

The tool driving element 5 is provided with a pair of projecting ribs 12which are approximately 1% to 11/2 times the width of the recesssections 10. These ribs 12 project into the recess sections 11 dividingthe recess sections 11 into two separate chambers 12a and 12b (seeFigure 1C) as well as separating the recess sections 10 into achambper`apartfromV the, recess sections 11 when the unit is in an inoperativeposition. The upper inner surface 36V ofjthe ribsv 12 t closely tothesurface 37 of the shoulders 34 and 35 of the sections-32 and 33.

A channel 13 of somewhat smaller diameter than the central channel' 14through which drilling mud passes to the cutting tool, opens intothechannel 14`at the upper end of the drilling unit. Thiswchannelpassesthrough the backing element 3V andterminates at a lixed'valve element orrestricted orifice 15 at the upper end of the tube ,4. Below this valveelement 15- an yannular opening 16 is formed between the wall of thetube 4 and theVY inner tube 6. At the upper end of driving element 5 isprovided passages 17 or extensionsl of recess 11 which connect thiscylindrical opening 16 with one end of the recess 11; It will be notedthat these passages 17 enter the recess 11 at correspondingdiametrically opposite positions of the recesses. At the lower end ofthis drilling unit, a ring 18 fitting around theA projecting tube 8covers the lowermost end of the recesses 11, but leaves open therecesses 10. This ring 18 is securedl over the driving element 5 bymeans of a plurality of screws 19, threaded into the drivingelement 5.

In the operation of this drilling unit as shown in Figure l, mud entersthe drilling unit at the upper end from the hose connection which willbe hereinafter described and passes down throughthe center of the tube 6to the cutting tool. A portion of the mud however which, enters the tube6, is by-passed through the channel 13 into the chamber 16 wherepressure isbuilt up, which pressure is dependent upon the relative sizeof the valve 15 and the size of the openings 71 through the cutting tool70. This cutting tool 70 may be of conventional shape and structure. Theopenings 71 communicate with passage 9 for passage of drilling mudthrough the unit.

As will readily be seen in Figure 2, the driving element 5 is mountedconcentrically and is partially rotatable within the lower end of thetube 4 with the projecting ribs 12 fitting into and forming separatechambers of the recesses and 11 with each of the recesses 11 dividedinto two sections by the ribs 12. When mud is being forced down into thechamber 16 and the pressure builds up in this chamber, thermud willforce its way into the recesses 11 through the passages 17. As'theserecesses 11 are formed withone edge wall constructed as a part of thecylinder 10A and the other edge wall formed by the rib 12, the pressurewhich is built up will cause these side walls to move apart in arotational movement. 'Ihe consequent rotation of the driving element 5,twists the tube 6. On suicient rotation ofthe driving element 5, thechambers formed by the recess sections 11 are opened to the chambersformed by the recess sections 10. This 'releases the pressure built upby the mud which may then pass out through the bottom of the recesssection 10. The torsional stiffness of the tube 6 which rigidlyinterconnects the backing element 3 and the driving element 5, will thenrotate the element 5 back to and beyond its position of rest, wherepressure can again be built up in the recess sections 11. It will beclear that the rapid action just described above, 4applies in eifect apulsating torque between the driving element 5 on the one hand, and theVrigid aggregation ofthe backing element 3, tube 4, and elements 32 and33 on the other hand, thereby periodically twisting the tube 6.

As mentioned previously, I prefer to make the inertia consisting ofelement 3, tube 4 and elements 32 and 33 of` the cylinder 10A, largecompared to the inertia of the driving element 5 and the tool mounted onit@ Operated as above indicated, the driving element then describes atorsional oscillation at a frequency which is determined byv'thetorsional stiffness of the tube 6 andthe inertia of 4 the drivingelement 5 in cooperation of the total inertia of the backing element 3,the tube 4 and the cylinder 10A.

It will be clear from the foregoing that the above described unitoperates in essence as a torsionally resonant system of two degrees offreedom, i.e. both element 5 and element 3 with its associatedstructures oscillate torsionally but in opposite directions and atangular amplitudes which are inversely proportional to their inertias.Therefore, if as I prefer to do, the inertia of element 3 and itsassociatedY structures is made large with respect to the inertia ofelement 5 and the tool it is moving, then this ratioV willV ensurelittle or substantially no Atorsional amplitude of element 3.

The advantages of such an arrangement become immediately apparent whenit is realized that the rotation force exerted by the tool in cuttingthe structure to be drilled must be backed up in some way if cutting isto be accomplished. In the normal rotary rig this backing is provided bythe surface mounting supporting the rig table and perforce such anarrangement meansthat the connection from there to the tool must besubstantially rigid. In the present invention, however, the torsional..oscillation of the tool and element 5 is backed up by an equal andopposite oscillation of element 3, so that the means used to support theunit need only support its weight and does not have to provide backingfor the forces exerted by the tool as would ordinarily be the case sincethese are effectively dynamically balanced by the simultaneous andopposing oscillation of element 3 and its associated structures. Theimportance of this fact with its application to the problem ofunderwater drilling will become even more apparent hereinafter.

While it may be assumed that the constant twisting of tube 6 wouldeventually result in its being fractured, this will not be the'case ifits dimensions are so chosen as` to result in a maximum ber'stress in itof not more than 10,000 lbs. sq./in. and the steel is of good quality.

The angular amplitude of element 5 and its frequency of oscillation aresomewhat a matter of design depending upon the work to which it is to beput, the maximum permissible diameter of the unit and the type ofcutting tool to be employed. Generally speaking, it is desirable to havethe angular amplitude such that the cutting teeth of the tool willtraverse a distance greater than the tooth spacing so that ridges in thestructure being cut will not build up between the teeth as cuttingproceeds.

With such an arrangement as has been described above, frequencies ofoscillation of the order of 3600 vibrations per minute can be readilybuilt up which ensures rapid cutting. If greater frequencies aredesired, as for instance frequencies up to say 7200 vibrations perminute I prefer to use an electrically operated drive such as is shownin my patent application Serial No. 275,496, now

Patent Number 2,803,433, led March 8, 1952 in connection with thesupporting elements hereinafter described.

By proper choice of frequency and amplitude the maximum velocity of thecutting teeth may be made far greater than is'possible where the toolmust be rotated from the surface. Consequently greater effectivenessA ofdiamond bits can be attained because with higher velocities on such bitsthe pressure may be reduced for equivalent cutting and the life of thediamond bit increased.

This drillunit which may be in the neighborhood of 200" long, issupported by a flexible tube 50 formed of a number of uniformunitsattached end to end with the number of units dependent on the depth ofthe hole being drilled. The unit which forms this iexible tube 50 has arubber or other water resistant flexible tube length 20 fixed securelyat its upper end about the downwardly projecting annular iiange 21 ofthe upper male member 22 by conventional means for bonding rubber tometal. This male member 22 is provided with a central opening23 enteringthe center of the tube-20 through which the drilling mud being suppliedto the drilling unit may pass. At the upper end ofthisfmaley member isathreaded pipe connection 24. At the lower end of this flexible pipe ortube 20, is rigidly secured a female member 25 with an upper annularflange 26 about which the inner side of the tube 20 is fixed. The femalemember 25 is provided with a lower annular flange 27 and a recessportion 28 which are shaped to receive the upper end of a maleconnecting element 22 or the upper end of the drilling unit. The annularflange 27 is shaped to project downwardly along the outside of the maleconnecting element and to fit over a series of O rings 29 fixed ingrooves about the male member 22. These O rings provide a water-tightconnection when a male and female connecting element are screwedtogether. The tube 20 as will be seen in Figure 5 is provided with aseries of longitudinally extending flexible steel wires 30, which extendthe length of the tube 20 and are connected at their upper ends bywelding or other suitable attaching means to the male member 22 and attheir lower end to the female member 25. This flexible tube 50 issecured to the drilling unit, (Figure l) by means of an interconnectingfemale section or member 25 and a male member or section 31 at the upperend of the drilling unit which is similar to the male sections of theconnecting elements shown in Figure 4. This drilling unit is supportedprimarily by the steel wires passing through the rubber walls 20, whichmay be selected in such number and strength as to be more than adequateto support the weight of the drilling unit. For instance, if thecarrying capacity equivalent to a 1%", 6 x 19 steel cable is desired, 501/a diameter steel wires incorporated in the walls of the tube wouldgive a cross sectional equivalent to the cable just mentioned.Ordinarily this amount of longitudinal reinforcing would not benecessary because the weight of the tool and driving element plus thehose would be less than a rotary drill pipe of equivalent capacity. Itwill be noted that this construction gives a flexible tube forconnecting the tool to the surface and yet has sufficient strength tosupport any weight likely to be encountered.

A pair of copper wires or other suitable insulated electrical conductors40 and 41 pass longitudinally through one rubber tube 20 and areconnected at their ends by insulated conducting elements to similarelectrical conductors 42 and 43 in the next adjacent tube 20respectively. The conductors 42 are connected one each to one half of asplit slip ring 44 which is positioned at the top of the male element 22and is insulated from it by an insulating element 45. The lower end ofthe wires 40 and 41 are connected through the insulated conductor 43 tobrush element 46 positioned at the lower end of the female element 25and insulated from it by the insulation 47. When a series of these unitsare connected end to end, electrical contacts will be made between thebrushes and the split rings permitting the use of this flexible tube tobe used in connection with a driving unit such as described in mycopending application Serial No.v 275,496, now Patent No. 2,803,433,patented August 20, 1957, mentioned above. In such an application ofthis flexible tube, the electrical conductors may be used to supplypower to the drilling unit, while the interior of this tube may be usedfor the transmission of drilling mud to the cutting tool element. Whensuch flexible tube is to be used in connection with a drilling unit,such as herein described, the electrical conductors will not be used.

The upper end of the supporting flexible tube when used in under waterearth drilling, passes upwardly through an opening in the well 48 of thebarge or supporting vessel (Fig. 7). j

The upper end of this supporting tube 50 is supported and secured to theusual type of rig, not shown. Concen'tric with the tube 50 is an outerflexible casing tube 51 which extends downwardly to a point just abovethe level of the ocean bottom and has bonded to its lower end a fitting52 threaded at its inner lower surface.

This fitting 52 screws on to a surface casing 53 corresponding to theusual type of surface casing used in wells on dry land. A fitting 54 isbonded to the upper end of this tube and is provided with threads at itsupper end for securing the tube and fitting to the steel tubing S5. Thissteel tubing 55 extends upwards through a platform S6 supported onstanchions 57 and terminates at its upper end in an outwardly extendingflange 61. Slidingly fitting about this steel tube 55, above the plat`form 56 is a curved seating ring 58 with its lower curved surfacefitting a complementary corresponding surface of the annular ring 59which in turn is secured about the opening through which the steel tube55 passes by a series of bolts 60. A helical spring 62 is positionedabout the steel tube 55 between the ange 61 and the curved seating ring58, exerting an upward pressure on the steel tube 55. The platform 56forms the bottom of the trough having side walls 63 which open at oneside into a sluice-way 64. The sluice-way 64 in turn opens into somesuitable tank (not shown), on the barge, which acts as a slush pitsimilar to the type used in the dry land operation.

It will be noted that in this construction the cooperation of the rings58 and 59 permit the tube 51 to stay in its proper position irrespectiveof the rolling of the barge.

It will be clear from the above that the arrangement just describedperforms two essential functions in that it provides a means wherebydrilling mud may be supplied to tube 50 and hence to the tool byconventional means and also provides a means of returning the mud fromthe tool to the slush pit via the annular space between the walls of thehole and tube 50 and between the tube 50 and the enclosing tube 53 tothe slush pit from which it may be reused.

In starting such a drilling operation, the barge 49 carrying the aboveequipment would be secured at the desired location as shown in Figure 10by semi-permanent moorings 65 spaced conveniently 120 degrees apart tominimize motion of the barge with respect to the chosen location. Thetool and tool driving unit would then be lowered through the well anddrilling commenced simply using water in place of drilling mud until ahole of sufficient depth has been drilled to permit of setting thebottom casing 53 (Figure 9), and cementing it in place. If care is takento select a calm day for these initial operations, no difficulty shouldbe encountered in drilling the hole for the surface casing, installingit and cementing it in place.

Once the above casing has been well cemented in place', the connectionof the tube 51 to casing 53 may be made by a diver and the upper end ofthe tube 51 connected to the tube 55 by screwing the latter to it.

It will be noted that the above arrangement makes a very flexible andconvenient method for drilling. For instance, if during the course ofdrilling the weather should become adverse, tube 55 may simply beunscrewed from the upper end of tube 51, after withdrawing tube 50 andthe tool and driving mechanism which it supports, after which tube 51may be temporarily capped by screwing a cap on its upper end and droppedoverboard attached to a mooring float so that it can be readilyretrieved later, and the barge may proceed to port to await betterweather. In the meantime, hose 5l being of flexible material andsubmerged in addition, is no menace to navigation. When the weathermoderates, operations can readily be resumed by reconnecting hose 51 totube 55 after removing the barge.

It will be clear that drilling conducted as indicated above is notlimited by the depth of water at the desired location as long as it isnot too great for a diver to work in it, which may be as much as -200feet, or very much greater depths than is possible where permanentplatforms must be built to accommodate conventional drilling equipment.Not only is the cost of the drilling platform avoided, but operationscan be sus- Apende'd andreinitiated ata new location witha minimum of'time and expense. been Completed, the top of the casing may beconnected to a valve, and suitable piping laid on the bottom to transmitthe oil to some shore location so that subsequent Weather conditionswill have no effect on utilizing the output of the Well and getting itto market.

With a mooring arrangement. such as is shown inFigure l0, even underadverse weather conditions,` it is not likely that the motion of thebarge would exceed l feet either side of the chosen position. Thus in adepth of Water as'littleV as 50 feet, this would only mean a possiblemaximum angle away from the vertical of about Furthermore, when theWell. hasV 11.3 degrees and thiswould only involve an elongation 'of thetube 51 by about one footto take care of it, which may easily be Withinthe contracting abilityr of spring. 62. insofar as tube 50 is concerned,the natural stretch of it as limited by the Wires embedded within itunderV load would undoubtedly be sufficient to take up such a smallchange especially. Vwhen drilling at more than the shallowest depths. Ingreater depths than 50 feet of Water, the angle would be proportionallyless and the' take up or release required by spring 62 would be no moreand perhaps less than would be encountered in fty feet of water.

Having now described my invention, I claim:

l. A means for earth boring, including a iluid drilling unit having apair of mass elements, a resilient member interconnecting said masselements, means for establishing said mass elements in resonantoscillation in opposite directions n a dynamic state of equilibriumincluding an expandible chamber partially formed by said mass elementsand adapted on expansion. to move said elements in said directions, saidlast mentioned means also including a iluid conduit and valve meansadapted to permit passage of lluid through said chamber for periodicexpansion thereof, and a cutting tool secured to one of said masselements.

2. A means for underwater earth boring adapted to be operated from afloating supporting structure comprising a fluid drilling unit having apair of mass elements, a resilient member interconnecting said masselements, means for establishing said mass elements and resilient memberin resonant oscillation wherein the oscillation of one element willdynamically balance the oscillation of the other element, said meansincluding an expandible means engaging each of said mass elements, aflexible tubular means secured at one end to the unit and at the otherend to said supporting structure for supplying fluid under pressure tothe expandible means causing said expandible means to expand and movesaid mass elements, pressure release means connected to the expandiblemeans for periodically releasing fluid from the expandible means, and acutting tool secured to one of said mass elements.

3. A means for earth boring comprising a drilling unit having a pair ofcoaxial tubular mass elements, means including coacting walls formed bysaid elements adapted to be moved arcuately with respect to the axis ofthe tubular mass elements to form between said mass elements anexpandible chamber, means for introducing lluid pressure into saidchamber for expansion of the same, means forming pressure releaseoutlets in said chamber, means including elastic means interconnectingsaid mass elements adapted to cooperate with said'mass elements onmovement of the said wall elements to establish a torsionally resonantoscillating system, aV cutting tool connected to and operated by one ofsaid mass elements, and means for supplying drilling mud to saiddrilling unit.

4. A means for earth boring comprising a drilling unit having a pair ofcoaxial tubular mass elements,

'means including coacting walls formed by said elements adapted'to bemoved arcuatelywith respect .to thevaxis of the tubular mass elements toform between said mass elements an expandible chamber, Ymeans forintroducing fluid pressure into said chamberfor expansion, of the same,means forming pressure release outlets in said chamber, means including`a torsionally resilient tube having each end rigidly fixed to `adifferent one of said mass elements interconnecting the same and adaptedto cooperate with said mass elements, on movement of said wall elementsto establish a torsionally resonant oscillating system, a cutting toolconnected andv operated by one of said mass elements, an-d means forsupplying drilling mud to s'aid drilling unit.

5. In a means for underwater earth boring, a flexible unit forsupporting and supplying power to a drilling unit, comprising aplurality of ilexib-le tubular members having interconnecting male andfemale elements at their ends, a plurality of longitudinally extendingreinforcing metal wires in said tubular members anchored at their endsto sai-d male and female elements, an electrical conductor passinglongitudinally through each of said tubular members and terminating inthe male and female members at its ends in contacting members adapted tomake an electrical contact with said contacting members of. adjacenttubular members.

6. In a means for underwater earth boring, a flexible unit extendingfrom a supporting structure at the Water surface to a drilling unitwithin the earth, comprising a flexible tubular element for supportingand conveying drilling lluid to the drilling unit from the supportingstructure, an outer flexible tubular element coaxial with the portion ofthe first mentioned element in the water, means including a springmember for resiliently and pivotally securing the upper end of saidouter llexible element in said supporting structure and means for se'-curing the outer flexible tubularV element to the earth at its lowerend.

7. ln a means for underwater earth boring, means for pivotally andresiliently supporting an upwardly extending flexible tubular elementcomprising a supporting structure, a rigid tubular end piece fixed tothe upper end of said element with the end piece having an inwardlyextending flange at its upper end, a bearing means spaced from saidflange seating means secured to said supporting structure coaxial withand adapted to pivotally engage said bearing means, and spring meansinterposit'ioned between said flange and bearing means resilientlysupporting said end piece.

8. A structure as set forth in claim 7 wherein said seating meanscomprises an annular ring having'a curved upper surface secured to thesupporting structureV with said bearing ring having a curved lowersurface complementary to and freely pivotable on said curveduppersurface.

9. ln a system for drilling, a resonant Vstructure having a torsionallyresilient elongated member, a pair of mass elements secure-:l one eachto each end of said member, said member and elements having an inherentresonant frequency of oscillation about the longitudinal axis of saidelongated member, and means for establishing said structure in saidresonant oscillation comprising a iluid pressure expandable chamberpartially formed by each mass element and having a fluid inlet andpressure release outlet whereby on intro-duction of fluid pressure intosaid chamber it will periodically expand and contract at said frequency.y

10. A device as set forth in claim 2 providing resilient means securingsaid llexible tubular means at its upper end to said supportingstructure.

ll. A means for earth boring comprising` a torque tube, a pair ofcoaxial cylindrical massvmembers coaxial with and firmly secured atspaced sections of said tube, means partially formed by and positionedbetween said members forming an expandible chamber, With oppositemovable portions ofsaid chamber positioned-.normality and formed-by eachof said members adaptedwhen moved to provide through said members"torque forces to said tube, means for supplying Huid to said chamberfor expansion thereof, means for releasing periodically said iluid fromsaid chamber, and a cutting tool secured to one end of said tube.

12. Means for torsionally operating a drilling bit, comprising a torquetube, means providing a driving connection from the torque tube to thedrilling bit, two tubes coaxial with said torque tube one about theother and both about the torque tube, one of said two tubes rmlyattached to one end and the other to the other end of said torque tube,and fluid operated expandible means between said tubes and partiallyformed thereby adapted to be periodically expanded and when expandedprovide force components perpendicular to the torque tube at the ends ofthe radius of the torque tube comprising means forming a longitudinalrecess in one of the two tubes and a longitudinal projection from theother of the two tubes partially occupying said recess and cooperatingtherewith to form an expandible chamber, means forming a uid connectionfrom said torque tube to said chamber whereby a portion of fluid owingthrough said torque tube may be diverted for introduction into andexpansion of said chamber, and means forming a pressure release openingfor uid in said chamber comprising an opening positioned to be uncoveredwhen said chamber has expanded to a selected volume.

13. A means for earth boring comprising a drilling unit having a cuttingtool, a pair of coaxial cylindrical mass elements with one having amoment of inertia greater than the other, torsionally resilient meansinterconnecting said elements, means formed in part by each elementproviding an expandible chamber adapted to be expanded on relativemovement of said elements, comprising means forming a longitudinalextending recess in one element with a longitudinally extending angeprojecting from the other element and forming a movable wall in theother element, means for introducing fluid under pressure into saidchamber for expansion thereof, means for periodically releasing said uidfrom said chamber and a cutting tool secured to said torsionallyresilient means.

14. A means for earth boring including movable masses fixed to andcoupled by a resilient member, means for providing periodic torsionalforces for oscillating said resilient member and thereby oscillatingsaid masses including expandible means formed between said masses withopposing movable portions of the expandible means formed by andpositioned normal to the direction of movement of each of said masses,said movable portions adapted when moved to provide torque forces tosaid resilient member, means for supplying uid for expansion of saidexpandible means, means for periodically releasing said fluid, and acutting tool secured to one of said masses.

15. A means for earth boring comprising a pair of mass elements, aresilient member interconnecting the mass elements, walls forming anexpandible chamber with at least a portion of the walls formed by themass elements, means including a uid conduit and valve connected to thechamber and adapted periodically to direct uid under pressure to thechamber for expanding the chamber to establish said mass elements inresonant oscillation in opposite directions in a dynamic state ofequilibrium, and a cutting tool secured to one of the mass elements.

References Cited in the ile of this patent UNITED STATES PATENTS OTHERREFERENCES Vibration Problems in Engineering, pages 9-12 inclusive,second edition, by Timoshenko, published July 1937.

